Flat screen color displays present in the art normally use illumination in the form of white light. The white light falls on the display such as LCD which uses color filters to depict colors. Color filters reduce efficiency of the display since large amount of light is absorbed. Another disadvantage is that because of the color filters the transmittance of the display is very low.
Another method known in the art is to stack dyed nematic crystal panels one after the other. White light is passed through them. Each layer subtracts some amount of the red, blue and green respectively from the white light according to the voltage applied to it and displays the colored image. But this also has a disadvantage of loss of light and hence reduced efficiency. It also suffers from parallax errors.
Large displays such as advertisement hoardings are presently made using white backlights and a colored picture on top of it. The color pigments in the colored picture reduce efficiency of the display.
Thus it is required to manufacture multicolored illuminators, so as to improve the efficiency of display systems like TVs and hoardings.